This invention relates to ultraviolet curable coating compositions and methods for making same. More particularly, this invention relates to a process for rendering titanium dioxide useful in ultraviolet curable coatings applications.
Heretofore, the use of titanium dioxide in ultraviolet curing systems has been largely prohibited, apparently because of the ultraviolet reflective nature of titanium dioxide pigments. See, for example, U.S. Pat. No. 3,632,527, which discloses one method of modifying titanium dioxide pigments to allow their use in certain actinic light systems.
When titanium dioxide pigments have been incorporated into ultraviolet curing coatings, exposure of the coatings to radiation under standard conditions has resulted in coatings with deficient cure properties. In particular, the coatings lack adhesion and chemical resistance of all types.
U.S. Pat. No. 3,048,530 discloses the preparation of vinyl acetate emulsions in the presence of titanium dioxide, utilizing ultraviolet light to enhance cure rates. However, there is no disclosure of the use of the resulting product in ultraviolet curable coatings compositions.
It is an object of this invention to prepare titanium dioxide pigment systems which may be utilized in ultraviolet curable coatings applications.
It is another object of this invention to prepare ultraviolet curable titanium dioxide-based coating compositions which have improved adhesion and cure properties when compared to the prior art titanium dioxide-based systems.
These and other objectives are obtained by preparing the compositions of the instant invention.